Lateral periodicity and elastic stress relaxation in GaInAsP quantum wires on InP investigated by x-ray diffractometry

Abstract

Synchrotron x-ray diffractometry has been used to investigate GaInAsP quantum wire structures on InP with a quantum well layer between the substrate and the wire. The lateral periodicity was determined with high accuracy. An elastic stress relaxation, which occurs near the free surface of the sidewalls, was observed. It results in deformation gradients in the wires, which influence the distribution of the diffracted intensity in reciprocal space.

Elastic stress relaxation in GaInAsP quantum wires on InP

“…A semi-quantitative agreement of the observed diffraction patterns with the kinematical calculations is obtained. The small shifts of the PL lines in the free standing structures correspond roughly to the expected value [15]. The remaining difference between the calculated elastic contribution E g (calc.)…”

“…The diffraction of x-rays by a quantum wire array can be described in first approximation in the kinematical limit in analogy to the Bragg diffraction from an atomic lattice [15,18]. The superstructure along the surface together with the truncation of the sample at the surface [19] leads to grating truncation rods (GTR).…”

“…At the European Synchrotron Radiation Facility, radiation from the beam line ID 19 (wavelength 1.5498 Å, double crystal monochromator Si (111), Si (111) analyser crystal or detector slits with an angular acceptance of 3 × 10 −3 ) was used for reciprocal space mapping. The geometrical relations in reciprocal space are discussed in [15].…”

“…For GaInAsP wire structures, an elastic relaxation near the free surface was observed. [15] In this paper, we have applied x-ray diffractometry to investigate the elastic stress relaxation in Ga 0.22 In 0.78 As 0.80 P 0.20 quantum wire structures with a typical wire width of 35 nm, which is also used for laser device structures. The influence of epitaxial overgrowth on the peak ¶ Author to whom correspondence should be addressed.…”